Today's KNOWLEDGE Share: Runaway Polymerisation

Today's KNOWLEDGE Share:

Runaway Polymerisation

Polymerisation is a chemical reaction, or process in which a monomer or a mixture of monomers is converted into a polymer such as polystyrene. Styrene polymerises slowly at normal ambient temperatures but very rapidly at elevated temperatures. It can be accelerated by heat, the lack of dissolved oxygen, the lack of a polymerisation inhibitor, and when contaminated by oxidising agents and most halides.

The polymerisation process is exothermic and, if the resulting heat is not removed, the bulk styrene temperature may rise to a level at which polymerisation is self-sustaining and very rapid. This is referred to as ‘runaway polymerisation’ and will usually be initiated by temperatures above 65°C. During a runaway polymerisation, the cargo will expand causing pressure to increase to the point

that vapour is released from tank vents or p/v valves. In some cases, the resulting build-up of pressure is sufficient to rupture the tank.

Case Study

On 28 September 2019, a cargo tank containing styrene monomer on board the Cayman Islands registered chemical tanker Stolt Groenland ruptured causing an explosion and fire. The ignition of the styrene monomer vapour resulted in a fireball. The rupture of the styrene monomer tank resulted from a runaway polymerisation that was initiated by elevated temperatures caused by heat transfer from other chemical cargoes.

The elevated temperatures caused the inhibitor, added to prevent the chemical’s polymerisation during the voyage, to deplete more rapidly than expected. Although the styrene monomer had not been stowed directly adjacent to heated cargo, the potential for heat transfer through intermediate tanks was not fully appreciated or assessed.

The tanker’s crew did not monitor the temperature of the styrene monomer during the voyage, and therefore were not aware of the increasingly dangerous situation.

What Went Wrong?

1-) The probability of heat being transferred from the other cargo tanks to the styrene monomer cargo was not fully considered during the planning and approval of the cargo stowage.

2-)Despite being a requirement in rules, the temperature of the styrene monomer was not monitored, and the temperature alarms available on the cargo monitoring system were not set. The crew also either did not notice, or did not recognise the significance of, the elevated temperatures of the cargoes discharged.

3-)The actions to be taken on encountering elevated temperatures in the styrene monomer cargo on board , which were stated on the procedure of inhibitor, were not done.

Source: Report on the investigation of the cargo tank explosion and fire on board the chemical tanker Stolt Groenland Ulsan, Republic of Korea 28 September 2019

Credits:Onur Ozutku

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#Polymerization #safety #fire #explosion #chemical #monitoring #runawayreaction #tanker #casestudy #riskassessment #vessel #cargo

Researchers Discover Plastic Eating Bacteria to Convert PET Bottles into Adipic Acid

Mountains of used plastic bottles get thrown away every day, but microbes could potentially tackle this problem.

Now, researchers in ACS Central Science report that they’ve developed a #plastic-eating E. coli that can efficiently turn polyethylene terephthalate (PET) waste into adipic acid, which is used to make nylon materials, drugs and fragrances.

Utilizing #Biosynthetic Pathways to Make Adipic Acid:

Previously, a team of researchers including Stephen Wallace engineered a strain of E. coli to transform the main component in old #PETbottles, terephthalic acid, into something tastier and more valuable: the vanilla flavor compound vanillin.

At the same time, other researchers engineered microbes to metabolize terephthalic acid into a variety of small molecules, including short acids. So, Wallace and a new team from the University of Edinburgh wanted to expand E. coli’s biosynthetic pathways to include the metabolism of terephthalic acid into adipic acid, a #feedstock for many everyday products that’s typically generated from fossil fuels using energy-intensive processes.

The team developed a new E. coli strain that produced #enzymes that could transform terephthalic acid into compounds such as #muconic acid and adipic acid. Then, to transform the muconic acid into adipic acid, they used a second type of E. coli, which produced hydrogen gas, and a palladium catalyst.

In experiments, the team found that attaching the engineered microbial cells to alginate hydrogel beads improved their efficiency, and up to 79% of the #terephthalicacid was converted into adipic acid. Using real-world samples of terephthalic acid from a discarded bottle and a coating taken from waste packaging labels, the engineered #Ecoli system efficiently produced #adipicacid. In the future, the researchers say they will look for pathways to biosynthesize additional higher-value products.

Source: American Chemical Society/specialchem

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Today's KNOWLEDGE Share:Crazing Effect on Polymers

Today's KNOWLEDGE Share

Polymer crazing does not immediately imply failure or loss of properties.

Due to fibrillar content, crazes can show a strength similar to the non-crazed material. Highly oriented fibrils can actually develop higher strength than the bulk material, so that stress at break may be retained.

On the other end, crazes are significant defects that will usually compromise elongation at break or impact performance, or drive a quicker failure in Fatigue, where fibrils are repeatedly beaten up, particularly at low or negative R ratios.

Source:Vito leo

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#polymers #crazingeffect #failure #propertieschange

Today's KNOWLEDGE Share : Recycled Plastics on Flooring:

Today's KNOWLEDGE Share

Recycled Plastics on Flooring:

One can use recycled plastics in various applications in today's world. It can be mixed with virgin,bitumen and other materials for road applications.Based on the requirements,relative humidity and condition of the road,the recycled plastic materials Polyolefins,pvc,polyolefins,engineering plastics and rubbers can be added.The thickness of the road and performance has to be met with the highways department norms.There have been quite number of roads have been tried on various materials and formulations in many places across the world.This has open the door to the recycled plastics to be filled in this market segment.

Recycled plastic materials are easy to source out for this flooring application and the demand is going to increase many fold when the government forms the regulations on recycled plastics for highways and construction applications.This will improve the quality of the existing road.There are couple of options can be tried out with fully recycled plastics for sport flooring application and with bitumen,the recycled plastics,fibers formulation also works out very well.With recycled rubbers and plastics,there will be a good result expected.These materials formulated when keep in mind of three things ie shocking absorption,slip resistant,long life of the road.

I have seen adding rock fibers with existing bitumen mixture,can increase the life term of the road to a few more years.In a way, we can add glass fibers waste on these applications too.PET bottle scrap,packaging recycled plastic materials do find its role in such applications.

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#plastics #recycledmaterials #recycledplastics #flooringsolutions

SABIC and Charge Amps to Manufacture EV Chargers with Renewable PC Housing

SABIC is enabling Charge Amps to manufacture electric vehicle (EV) chargers with a housing made from certified renewable #polycarbonate (PC), a first for the industry.

SABIC is supplying Charge Amps with its certified renewable grade LEXAN™ PC, supporting the EV charger provider’s commitment to develop the circular bioeconomy and help mitigate climate change issues.

Using Bio-feedstock that Does Not Compete with the Food Chain

SABIC’s renewable PC from its TRUCIRCLE™ portfolio is made from second-generation bio-feedstock that is not in competition with the food chain. The new industrial process contributes to reduce CO₂ emissions in manufacturing and installation and fully meets EVSE (Electric Vehicle Supply Equipment) regulations.

EVs are an essential component of #decarbonization strategies being adopted by governments and enterprises around the world. #EV is now an increasingly viable alternative to internal combustion engines to reduce the carbon footprint. The availability of charging facilities is recognized as one of the key factors associated with conversion to EVs.

Charge Amps Dawn is the latest #EVcharging station with a charging capacity of 22 kW in one socket, a certified MID (Measuring Instrument Directive) meter and 4G connectivity. Charge Amps Dawn Chassis contains in the range of 50 percent of ISCC PLUS certified #biobasedrenewable material from SABIC. The collaboration with the Nordic manufacturer that has a strong focus on sustainability throughout the whole production chain is yet another example of SABIC’s commitment to help accelerate the world’s shift to electric power, encapsulated in the company’s BLUEHERO™ initiative.

On top of #sustainability gains, #EVcharger manufacturers can benefit from increased functional integration and design freedom. For example, inner panels, #indoorcabinets and #consoles can be produced from a #flameretardant (FR) PC to achieve dimensional stability, high impact resistance and aesthetic finishing. Furthermore, thin-wall FR capability can help reduce weight beyond that achieved by simply replacing metal, and can also free up space for additional components.

#LEXAN™ PC is durable and weather resistant and can provide significant manufacturing cost reductions. It enables charger makers to simplify #production processes by using high-speed, high-volume #injectionmolding, and eliminates typical secondary operations that would otherwise be required for metals.

Source:Sabic/Omnexus-specialchem

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Today's KNOWLEDGE Share: Carbon Fiber Hat

Today's KNOWLEDGE Share

Carbon Fiber Hat

Picture this: you finally managed to buy the carbon fiber bike of your dreams... Now you just need a bottle holder! Would you choose a polymeric/metal one? NO, OF COURSE NOT!

Now why not add a lightweight and sleek carbon fiber fedora to your outfit? Plus, it's a conversation starter, as people are bound to ask, "Is your hat made of carbon fiber? That's so cool!" So, if you want to stand out from the crowd and rock a hat that's both stylish and innovative, a carbon fiber fedora is the way to go!

Or you might want to have a carbon fiber knuckle for personal protection with a touch of innovation. After all, nothing can bring more joyfulness to a "composites-head" than using your favorite material to beat the shit of some criminals!

If you are a die hard composites fan and did not get excited about these products... Come on! 
Sometimes it is not just a question of necessity... It's a matter of why not.... And some spare money, of course!

Source:#managingcomposites 

#thenativelab

#composites #carbonfiber

Today's KNOWLEDGE Share: Glass filled materials

Today's KNOWLEDGE Share

Ever wondered why fibers in GF filled materials always end up with an L/D of about 20 ?

If you consider a diluted case (to avoid fiber-fiber damage), and also forget for a moment the fibers pinned in the frozen skin that could snap in bending mode, you are left with the effect of flow shear stress on fiber damage.

And it turns out that fiber rotation due to shear produces a cyclic switch from tension to compression as shown in the picture. While the tension will never do any harm to the glass fiber (far too low), the compression load will trigger buckling and will snap the fibers just like you can snap raw spaghetti between your fingers ! At L/D=20 the buckling load threshold is so high that damage by flow becomes unlikely.

Source:Vito leo

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#plastics #glassfiber #injectionmolding #compression #fiberdamage